کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
31594 | 44823 | 2013 | 12 صفحه PDF | دانلود رایگان |

Glycogen and compatible solutes are the major polymeric and soluble carbohydrates in cyanobacteria and function as energy reserves and osmoprotectants, respectively. Glycogen synthase null mutants (glgA-I glgA-II) were constructed in the cyanobacterium Synechococcus sp. strain PCC 7002. Under standard conditions the double mutant produced no glycogen and more soluble sugars. When grown under hypersaline conditions, the glgA-I glgA-II mutant accumulated 1.8-fold more soluble sugars (sucrose and glucosylglycer-(ol/ate)) than WT, and these cells spontaneously excreted soluble sugars into the medium at high levels without the need for additional transporters. An average of 27% more soluble sugars was released from the glgA-I glgA-II mutant than WT by hypo-osmotic shock. Extracellular vesicles budding from the outer membrane were observed by transmission electron microscopy in glgA-I glgA-II cells grown under hypersaline conditions. The glgA-I glgA-II mutant serves as a starting point for developing cell factories for photosynthetic production and excretion of sugars.
► A glycogen synthase null strain accumulated more soluble sugars than the wild type.
► In hypersaline medium glgA mutants produced and excreted more soluble sugars than wild type.
► In hypersaline medium the glgA-I glgA-II mutant produced membrane-enveloped, vesicular structures.
► The effects of nitrogen-starvation were less severe in glgA mutants than in wild type.
► A model predicts that 39% of photosynthetic capacity can be used for biofuels without affecting growth.
Journal: Metabolic Engineering - Volume 16, March 2013, Pages 56–67